Multicolor, multilayer photographic elements are well known in the art of color photography. Usually, these photographic elements have three different selectively sensitized silver halide emulsion layers coated on one side of a single support. The vehicle used for these emulsion layers is normally a hydrophilic colloid, such as gelatin. One emulsion layer is blue-sensitive, another green-sensitive and another red-sensitive. Although these layers can be arranged on a support in any order, they are most commonly arranged with the support coated in succession with the red-sensitized layer, the green-sensitized layer and the blue-sensitized layer (advantageously with a bleachable blue light-absorbing filter layer between the blue-sensitive layer and the green-sensitized layer) or with the opposite arrangement and no filter layer. Colored photographic images are formed from latent images in the silver halide emulsion layers during color development by the coupling of oxidized aromatic primary amine color developing agent with couplers present either in the color developer solution or incorporated in the appropriate light-sensitive layers. Color photographic elements containing dye images usually utilize a phenolic or naphtholic coupler that forms a cyan dye in the red-sensitized emulsion layer, a pyrazolone or cyanoacetyl derivative coupler that forms a magenta dye in the green-sensitized emulsion layer and an acetylamide coupler that forms a yellow dye in the blue-sensitive emulsion layer. Diffusible couplers are used in color developer solutions. Nondiffusing couplers are incorporated in photographic emulsion layers. When the dye image formed is to be used in situ, couplers are selected which form non-diffusing dyes. For image transfer color processes, couplers are used which will produce diffusible dyes capable of being mordanted or fixed in the receiving sheet.
In the production of color photographic images, it is necessary to remove the silver image which is formed coincident with the dye image. This can be done by oxidizing the silver by means of a suitable oxidizing agent, commonly referred to as a bleaching agent, in the presence of halide ion; followed by dissolving the silver halide so formed in a silver halide solvent, commonly referred to as a fixing agent. Alternatively, the bleaching agent and fixing agent can be combined in a bleach-fixing solution and the silver removed in one step by use of such solution.
A commercially important process intended for use with color reversal photographic elements which contain the couplers in the silver halide emulsion layers, or in layers contiguous thereto, utilizes, in order, the following processing baths: first developer, wash, reversal bath, color developer, bleach, fix, wash and stabilizer. In this process, the first developer reduces the exposed silver halide to metallic silver; the reversal bath nucleates the silver halide that remains after first development, the color developer converts the nucleated silver halide to metallic silver and forms the dye images, the bleach converts all metallic silver to silver halide, the fix converts the silver halide into soluble silver complexes that are washed from the element, and the stabilizing bath improves image dye stability.
In one particularly advantageous form of the aforesaid color reversal process, a bleach-accelerating bath is employed between the color developing bath and the bleaching bath. Such a bleach-accelerating bath is also referred to in the photographic field as a "conditioning bath". It is used to "condition" the metallic silver, developed in the first and color developers, for complete oxidation to silver halide and to help preserve the acidity of the bleach solution by reducing carryover of color developer into the bleach. The conditioning bath contains, as an essential ingredient, an effective amount of a bleach-accelerating agent. This agent is imbibed into the emulsion layers of the photographic element during treatment with the conditioning bath and, accordingly, is present to exert its beneficial influence in situ when the photographic element enters the subsequent bleach bath.
A wide variety of effective bleach-accelerating agents are well known in the art of photographic color processing. Examples of particularly effective bleach-accelerating agents include aliphatic thiols, heterocyclic thiols, disulfides, thioethers, and persulfates. References describing specific agents which exibit very effective bleach-accelerating capabilities include British Patent No. 1,138,842 published Jan. 1, 1969 and U.S. Patent No. 3,893,858 issued July 8, 1975.
In carrying out the aforesaid color reversal process with the aid of a conditioning bath, a serious problem that is frequently encountered is deposition of scum on the photographic element as it is contacted with the conditioning bath. Formation of precipitates within the conditioning bath and deposition of such material on the walls of the conditioning bath tank is also a problem, but it is the formation of an adherent layer of scum on the photographic element itself that is of greatest concern. A number of factors are believed to influence such scum formation. For example, the formation of scum is significantly influenced by the extent of seasoning that has taken place in the process. Seasoning products released from the emulsion layers, or other layers, of the photographic element tend to build up in the processing baths. One seasoning product which is believed to be a significant source of scum formation is the coupling-off group 4-hydroxyphenyl--4'--phenylmethoxyphenyl sulfone. This anionic group is derived from a yellow coupler that is commonly used in color reversal films. In addition to the extent of seasoning, another feature which influences scum formation is the extent to which the photographic element comes into contact with transport rollers during processing. Such rollers tend to serve as places where scum-forming materials can accumulate and, by contact with the photographic element, may make it more susceptible to the deposition of scum.
Photographic films which are processed by color reversal processing methods often include an antistatic layer on the side of the film opposite to the emulsion layers. Antistatic layers which are of particular commercial importance include those described in Kelley et al, U.S. Pat. No. 4,070,189 issued Jan. 24, 1978. As described in this patent, the antistatic compositions comprise a highly cross-linked vinylbenzyl quaternary ammonium polymer and a hydrophobic binder. Reversal films containing such antistatic layers are especially prone to scum formation. Deposition of the layer of scum takes place primarily on the base side of the film; apparently influenced, at least in part, by attraction between cationic groups in the antistatic layer and anionic seasoning products carried into the conditioning bath.
While scum can form in any of a variety of photographic processing baths, the problem of scum formation is particularly acute in the above-described bleach-accelerating or conditioning baths. Overcoming this problem has proved to be a particularly formidable task. Attempts have been made to solve the problem through incorporation in the conditioning bath of certain nonionic surfactants as described, for example, in an article entitled "Conditioning Baths For Use In Photographic Processing", published in Research Disclosure, Vol. 191, Item 19104, March, 1980. However, addition of agents to the bleach-accelerating bath which might serve to inhibit scum formation is severely inhibited by the requirements that the agent employed not only be free of adverse effects on the sensitometry of the photographic film, but also that it not inhibit or detract from the bleach-accelerating capability of the bleach-accelerating agent and that it be fully compatible with concentrated forms of the bleach-accelerating bath in order to facilitate packaging, shipping and handling.
It is toward the objective of providing an improved bleach-accelerating composition which does an effective job of accelerating the bleaching action of the subsequently utilized bleaching agent, and which eliminates or at least reduces the deposition of scum in the bleach-accelerating bath, that the present invention is directed.